CRC1 confers heat tolerance by modulating meiotic DSB formation and repair in rice

CENTRAL REGION COMPONENT1 (CRC1), a key element of synaptonemal complex (SC) in rice (Oryza sativa L.), plays a crucial role in meiotic double-strand break (DSB) formation and repairing. However, its molecular functions remain incompletely characterized. In the present study, a thermosensitive low-fertility mutant was identified, and the corresponding gene CRC1 was cloned using a MutMap+-based approach. The mutant crc1-t carrying a single-base substitution in the AAA-ATPase domain of CRC1 exhibited severely reduced fertility under high temperature, with partial restoration under normal conditions. Consistent with this observation, defects in bivalent formation in crc1-t were also partially rescued at normal temperatures. Immunofluorescence analysis revealed a notable reduction in the foci of γH2AX, RPAla, DMC1, RAD51, HEI10, and ZEP1 on crc1-t meiotic chromosomes, particularly under high temperatures, suggesting that normal temperature partially restores the meiotic DSB formation, repairing, and SC assembly in crc1-t. Yeast two-hybrid assays demonstrated that the interaction between CRC1-T and P31^comet, ZEP1 and PAIR1 gradually weakened with rising temperature and were nearly abolished at 36°C, whereas the wild-type CRC1 maintained stable interactions under the same conditions. These results imply that the non-frameshift mutation in the AAA-ATPase domain of CRC1 disrupts its protein partnerships under heat stress, leading to defects in DSB formation and DNA repair, thereby conferring thermosensitivity of crc1-t. Our findings elucidate a mechanism by which CRC1 responds to temperature stress by modulating DSB dynamics and SC stability during rice meiosis.